feat(ses): Tame ModuleSource

packages/ses/src/commons.js

@@ -26,6 +26,7 @@ export const {
   JSON,
   Map,
   Math,
+  ModuleSource,
   Number,
   Object,
   Promise,

packages/ses/src/lockdown.js

@@ -46,6 +46,7 @@ import { makeSafeEvaluator } from './make-safe-evaluator.js';
 import { initialGlobalPropertyNames } from './permits.js';
 import { tameFunctionToString } from './tame-function-tostring.js';
 import { tameDomains } from './tame-domains.js';
+import { tameModuleSource } from './tame-module-source.js';
 
 import { tameConsole } from './error/tame-console.js';
 import tameErrorConstructor from './error/tame-error-constructor.js';
@@ -267,6 +268,8 @@ export const repairIntrinsics = (options = {}) => {
 
   tameDomains(domainTaming);
 
+  tameModuleSource();
+
   // Replace Function.prototype.toString with one that recognizes
   // shimmed functions as honorary native functions.
   const markVirtualizedNativeFunction = tameFunctionToString();

packages/ses/src/tame-module-source.js

@@ -0,0 +1,35 @@
+import {
+  ModuleSource,
+  functionPrototype,
+  getPrototypeOf,
+  objectPrototype,
+  setPrototypeOf,
+} from './commons.js';
+
+export const tameModuleSource = () => {
+  if (ModuleSource !== undefined) {
+    // We introduce ModuleSource.[[Proto]] === AbstractModuleSource
+    // and ModuleSource.prototype.[[Proto]] === AbstractModuleSource.prototype
+    // if that layer is absent because the permitting system can more
+    // gracefully tolerate the absence of an expected prototype than the
+    // presence of an unexpected prototype,.
+    function AbstractModuleSource() {
+      // no-op safe to super()
+    }
+
+    const ModuleSourceProto = getPrototypeOf(ModuleSource);
+    if (ModuleSourceProto === functionPrototype) {
+      setPrototypeOf(ModuleSource, AbstractModuleSource);
+    }
+
+    const ModuleSourcePrototype = ModuleSource.prototype;
+    if (ModuleSourcePrototype !== undefined) {
+      // ModuleSource.prototype.__proto__ should be the
+      // AbstractModuleSource.prototype.
+      const ModuleSourcePrototypeProto = getPrototypeOf(ModuleSourcePrototype);
+      if (ModuleSourcePrototypeProto === objectPrototype) {
+        setPrototypeOf(ModuleSource.prototype, AbstractModuleSource.prototype);
+      }
+    }
+  }
+};